DNA encoding a truncated pneumogoccal surface protein (PspA)

Abstract

A purified pneumococcal surface protein A (PspA) comprises a truncated form of the PspA protein which is immunoprotective and contains the protective epitopes of PspA. The PspA protein is soluble in physiologic solution and lacks at least the cell membrane anchor region of the whole protein. The protein is formed by insertion-duplication of mutagenesis of S. pneumoniae with pspA gene and expression of the truncated protein into the growth medium.

What we claim is: 
     
       1. An isolated DNA molecule consisting of a nuclaotide sequence coding for an immunoprotective pneumococcal surface protein A (PspA) wherein said PspA comprises the sequence of FIG. 3 (SEQ ID NO: 2). 
     
     
       2. An isolated DNA molecule consisting of a nucleotide sequence coding for an α-helical coiled coil region of pneumocaccal surface protein A (PspA) wherein said PspA comprises the sequence of FIG. 3 (SEQ ID NO: 2). 
     
     
       3. An isolated DNA molecule consisting of a nucleotide sequence coding for a proline rich region and repeat region of pneumococcal surface protein A (PspA) wherein said PspA comprises the sequence of FIG. 3 (SEQ ID NO: 2). 
     
     
       4. An isolated DNA molecule consisting of a nucleotide sequence coding for a truncated form of whole pneumccoccal surface protein A (PspA) wherein said whole PspA comprises the sequence of FIG. 3 (SEQ ID NO: 2), wherein said truncated PspA contains immunoprotective epitopes and has the cell membrane anchor region absent therefrom. 
     
     
       5. An isolated DNA molecule consisting of a nucleotide sequence coding for a truncated form of whole pneumococcal surface protein A (PspA) wherein said whole PspA comprises the sequence of FIG. 3 (SEQ ID NO: 2) wherein said truncated PspA contains about 50% of the whole PspA protein and has the cell membrane anchor region, the repeats region, and the proline region absent therefrom. 
     
     
       6. An isolated DNA molecule consisting of a nucleotide sequence coding for a truncated form of whole pneumococcal surface protein A (PspA) said whole PspA comprises the sequence of FIG. 3 (SEQ ID NO: 2), wherein said truncated PspA contains immunoprotective epitopes and about 90% of the whole PspA protein and has the cell anchor region absent therefrom. 
     
     
       7. A method for forming an immunoprotective truncated pneumococcal surface protein A (PspA), which comprises: incorporating a vector comprising the isolated DNA molecule of claim 4 into a bacterium by transformation whereby said transformed bacterium expresses said DNA molecule,   growing said bacterium to effect expression of said truncated PspA protein, and   isolating said truncated PspA protein.   
     
     
       8. The method of claim 7 wherein said transformed bacterium is a Stretococcus pneumoniae strain, said strain is grown in a defined medium to effect expression of the truncated PspA protein into said medium, and the truncated PspA protein is isolated from the medium. 
     
     
       9. The method of claim 8 wherein said mutated strain is Streptococcus pneumoniae l strain JY2008 (ATCC Accession No. 55143). 
     
     
       10. The method of claim 7 wherein said transformed bacterium is a Eschoricha coli strain, said strain is grown to effect expression of the truncated PspA protein into the proplasm of said strain, and the truncated PspA protein is isolated from the periplasm of said strain. 
     
     
       11. The method of claim 10 wherein said strain is Escherichia coli strain JY4306 (ATCC Accession No. 68522). 
     
     
       12. The method of claim 7 wherein said isolated truncated PspA protein is purified by ion-exchange chromatography. 
     
     
       13. The method of claim 7 wherein said tranformed bacterium is selected from the group consisting of Streptococcus pneumoniae and Escherichia coli.